The clip of Jerry is not that great. It really takes the interview out of context, and makes him appear a supreme A-hole. Jerry was just being true to his humor, dry witticism. Its the sort of reaction you would expect out of him during the tv series. I'm sure you all noticed the occasional cracked smile and laughter from him as he was ripping into Larry.
As for Kramer's behaviour, meh. I think its very easy for us to judge public figures. Just imagine if someone filmed you in one of your worst moments as a person, be it acting racist, unethical, hypocritical, etc, and then having other people see it. I'll be the first to admit I've had breakdowns before, and have been just as bad before in my own rants. I've used terms like N**ger before definently in a racist context. Yet one of my closest friends is black, and I have no animosity towards anyone of any descent really. Kramer had a meltdown, acted inappropriately and has apologized for it. Unfortunately for him it ends his career, yet no more then a DUI ends some other peoples career. Unfortunately for him, and many people, it only takes one mistake to ruin your life in many ways, and theres no way to recover what was lost in a single moment of poor judgement.